Apparently the libraries SUNWvboxguest puts onto the system requires libXfixes.so.3 and libXext.so.6 but these libraries aren't on the system. I faked it by linking in older versions of these libraries and got the application to run; however, the libraries have updated versions for a reason and it isn't clear what the side effects of linking in an older version might be. For this reason, the links aren't a proper fix.

I don't see how the VBox.log for this session would apply so I didn't attach one.